I have tried cascading the HP SAS expanders in the past and never had solid results, in fact I never got better than flakey activity... from drives dropping to entire raidsets being corrupted. I eventually just ran single-linked connections from the 1880 to 2 seperate expanders via slot-based F-F SAS passthroughs. I believe odditory has tried this in the past but I don't know if he had any better results, but you can ask him.
This has been my experience as well -- and running single linked connections between RAID/HBA and expander is my preference. Originally I was daisy chaining two expanders via the SFF-8088 external connectors, and I narrowed the issue of multiple drives or entire raidsets suddenly dropping to expander #1 overheating. Which makes sense because its got to re-process all the traffic from expander #2, its not simply passing it through. So I didn't have lots of time or patience to spend getting daisy chaining working before just reverting to single links, but if I recall it began working okay after placing a 40x40x10mm fan on the heatsink of the first expander. And that episode prompted me to place fans on all my other HP Expanders, after seeing the difference it made.
Once again I'll point out that the HP Expander was designed for high-airflow HP servers, and as such ships without a fan on the heatsink. And many people have it running okay in non-HP cases, but that has more to do with the card not being pushed very hard in most home usage scenarios. Ultimately I suggest a fan on the heatsink for everyone not using the card in an HP or other high airflow server. And don't confuse having "good airflow" in your home case with high-airflow - there's a big difference - the latter is like having a blow dryer set on cold blowing across the expander's heatsink.
Really, everything that us home users and hobbyists choose to do with the card outside of using it in an HP server = we're on our own, no guarantees, requires testing and experimentation, wasn't designed to happen, YMMV, getting away with murder.